Research On All-optical Logic Gate For Advanced Modulation Formats

As a key element of the future large-capacity optical networks and no need for optical-electrical-optical(O-E-O),all-optical signal processing techniques becomes a hot research area at present.The all-optical logic gates is the important application in optical switching nodes,which is used for all optical computing,addressing,header recognition,data encoding,parity checking and data encryption.Under the impetus of the information technology rapid development,the demand for bandwidth is growing,which leads to higher requirements for the high transmission rate,high spectrum efficiency and high system capacity of signal transmission and signal processing.At present,the study of all-optical logic gates mainly focus on intensity modulation format signals,for the advanced modulation formats,only differential phase shift keying(DPSK)signals is mentioned in some researches.Combining with advanced modulation formats and all-optical signal processing technology,we study the differential quadrature phase shift keying(DQPSK)all-optical logic gate based on four wave mixing(FWM)in nonlinear media,and the main contents are as follows:1.The nonlinear effects in semiconductor optical amplifier(SOA)and highly nonlinear optical fiber(HNLF)are analyzed in theory.According to the reference,in the SOA,the paper has discussed the nonlinear effect of injection current and holding lights power.In the HNLF,the paper has discussed the nonlinear effect of nonlinear coefficient,attenuation and dispersion.The above analysis results is the reference for simulation setup.2.The paper achieves all-optical XOR logic gate and XNOR logic gate for DQPSK signal based on FWM in SOA.For the all-optical XOR logic gate,it's implemented by injecting two NRZ DQPSK input signals to the SOA based on degenerate FWM,and there are XOR logic relationship between the new generated idle and two input signals.For the all-optical XNOR logic gate,it's implemented by injecting NRZ DQPSK input signal and pump light to the SOA based on degenerate FWM,and there are XNOR logic relationship between the new generated idle and input signal.Except through the simulation setup to verify this solution,the paper also analysizes the effect of the bias current and optical signal rate by changing the two factors in SOA.3.The paper has first demonstrated the all-optical XOR logic gate and XNOR logic gate for DQPSK signal in HNLF.For there is no obvious signal rate limitation during the all-optical signal processing,and high coupling and low loss in HNLF.This paper has implements 100 gbit/s DQPSK signal all-optical XOR logic gate and XNOR logic gate in HNLF for the first time.And the paper has analyzed the effect of zero dispersion and the pump power on FWM performance.The research results provide valuable reference for design and analysis based on FWM in nonlinear medias and new opportunities for the research on all optical logic gates for advanced modulation formats.